Method and apparatus for multiplexing television signals
US4868658A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 13, 1985 |
| Grant date | Sep 19, 1989 |
| Priority date | — |
| Expiry date | Dec 13, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/0806
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A multiplexer for compressing two television programs into the bandwidth normally required for a single television signal is disclosed wherein vertically adjacent lines in the odd and even field of each frame are summed and differenced in pairs having the same color subcarrier phase. "Line pair signals" respectively comprising the sum and difference of each line pair are then formed after the difference signal is time compressed without an overall increase in bandwdth. The line pair signals for each frame of one program are alternately transmitted with the line pair signals of a frame from the second program. The line pair signals of a video frame are fewer in number and longer in duration than NTSC field lines. Timing is such that one frame of both programs is transmitted during the time allotted to the transmission of one frame under the NTSC standard. The lines from odd fields of each program are reconstructed after transmission by adding the appropriate difference signals and sum signals. The lines from even fields are reconstructed by differencing the sum signals and the difference signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.